The Greek philosopher Heraclitus, who lived in the first century BCE, was quoted as saying: “Change is the only constant in life.”
Normally, people react to change by expecting it to end soon, whereafter things will return to normal. Disruptive change, however, happens when an event or chain of events require a fundamental and permanent change of existing business models.
Climate change and global warming are exactly such a disruptive force; they have a profound and permanent effect on livestock farming globally. Extreme weather events, failure to respond to climate change, and biodiversity loss are now rated amongst the greatest dangers to the health of life and humanity on the planet.
There is sufficient scientific evidence that climate change and global warming have
changed the production environment and production base of livestock farming in Southern Africa dramatically over the past two decades, which can be described as having a potentially disruptive effect on livestock production and food security.
The more marked changes include a 1°C increase in average temperature per annum (compared with 0,65°C globally), more erratic and extreme rainfall as the wet periods become wetter and dry periods last longer and become drier, and an unprecedented increase in the concentration of carbon dioxide (CO2)in the atmosphere. The effects of these are:
- Livestock have to endure increased heat stress;
- Increased rainwater run-off with increased soil erosion;
- Longer and more intense climatic droughts; and
- Unchecked bush encroachment, decreasing the productivity and health of both savannas and grasslands.
On top of the scourge of climate change, livestock producers also have to grapple with natural resource degradation due to years of incorrect veld and grazing management. It is estimated that the average nett primary productivity in South Africa decreased by an average of 29kg of carbon/ha/year in the period from 1981 to 2003.
Meanwhile, South Africa’s population has been forecast to grow from 54 million currently to 65 million in 2050, although there are projections of much higher numbers.
The global outlook is just as staggering, with a projected increase from the current 7,8 billion people to 9,7 billion over the next three decades. The result for South Africa is that the livestock industry will have to increase its capacity to feed the country while a disruptive change in the production environment is taking place.
Against these mounting odds, livestock farmers will have to become more sustainable and resilient, and less prone to variable climate. The answer to these challenges is regenerative agriculture. Regenerative farming applies principles and practices that increase biodiversity, enrich soils, improve the water cycle, and enhance ecosystem services.
At the same time, it offers increased yields and resilience to a variable climate. In short, it strives to rebuild and restore ecosystem function.
Above the ground diversity
Plant biodiversity and veld condition are directly connected. As plant biodiversity of the veld improves, veld condition improves, and vice versa. Improved veld condition offers the following benefits to the livestock farmer:
- Less rainwater run-off;
- Improved water infiltration into the soil with more plant-available water;
- Improved soil health;
- A wide variety of highly productive, palatable and nutritious plant species (increased biodiversity);
- Higher and more stable fodder production;
- Improved drought tolerance, resilience and endurance;
- Higher, more stable animal performance; and
- Improved and more stable profitability.
Soil health, below-ground biodiversity
It is only recently that grassland and pasture scientists have started to study the life below ground in earnest. The preliminary results are startling, to say the least.
Historically, there was a firm belief that it is mainly the plant organic matter content in the soil that plays a role in soil health. We now know otherwise. Life in and amongst the soil consists of micro-organisms (collectively called the soil’s microbiome), of which bacteria and fungi are the most numerous and important.
In the past, it was believed that the microbiome was more or less evenly distributed throughout the soil, but recent studies have demonstrated increased microbial diversity in the rhizosphere (the area in and between the roots of plants), compared with the bulk soil.
Plant roots excrete so-called root exudates, which some of the bacteria and fungi feed on in exchange for nutrients provided by and through the microbiome through an interdependent symbiotic relationship. Plant rhizospheres are thus hotspots of microbial activity and carbon sequestration within the soil in the form of microbial organic matter, which is much more than plant organic matter.
Studies further indicate that each plant species is the architect of the structure and species composition of its specific rhizosphere-associated microbial populations.
It is thus hypothesised that above-ground biodiversity goes hand in hand with below-ground microbiome biodiversity. Above-ground ecosystem degradation thus also leads to below-ground ecosystem degradation, and vice versa. A farmer who looks after the health of the veld thus gains healthy soil, as the two are closely interconnected.
Bush encroachment and alien invasion
There has been a rapid expansion in the density of indigenous and alien bush species in South Africa over the past 30 years. This is having the following negative effects on ecosystem function from a livestock production perspective:
- The woody plants compete with the herbaceous layer for resources and space. As woody plants’ density increases, it gradually suppresses and reduces the cover and species composition of the grass, leading to a reduction in the herbaceous grazing capacity and a decrease in biodiversity;
- At high densities, woody plants rapidly exhaust the rainwater in the soil, leading to shorter periods of available soil water. This gives rise to the woody plants dropping their leaves more often and for longer periods due to a shortage of water. This is detrimental to browsers, as it leads to reduced browsing capacity. On top of that, the bush often becomes so dense that animals are prevented from accessing it to browse or graze; and
- The high water usage of dense woody cover leads to reduced groundwater recharge, with boreholes drying up.
Bush control thus deserves serious attention.
On the upside, woody plants remove carbon from the atmosphere and capture it in their roots, stems and other parts, and therefore an increase in bush density may be seen as a benefit to carbon sequestration.
The question is rightly asked whether the control of woody plants is not counterproductive in terms of this carbon sequestration. A report published by the Department of Environmental Affairs in 2019 investigated this issue and came to the following conclusion:
“[…] addressing bush encroachment would outweigh the mitigation benefit of allowing
it to proceed.
While the exact amount of carbon sequestered through bush encroachment in South Africa is unknown, even if it were substantial, the risk of losing biodiversity and further degrading ecosystem services [by] allowing bush encroachment to continue unheeded is considered unacceptable.
“Moreover, the potential risk to biodiversity of allowing bush encroachment would contradict the commitments made under the UN Convention on Biological Diversity. It is clear that bush encroachment should be considered a form of land degradation under the UN commitments, and that other, less damaging, emission reduction opportunities should be employed to meet those targets.”
More and more international field studies indicate that the restoration of degraded rangeland greatly increases carbon capture and storage rates in the soil.
For example, it is estimated that soils have the capacity to store about 2,3 times more carbon, as organic matter, than the carbon in atmospheric CO2, and 3,5 times more than the carbon in all living terrestrial plants.
As was mentioned, soil microbial communities that exist in symbiosis with plants play a major role in biogeochemical cycles by influencing carbon and nutrient cycling. The better this plant-soil interaction, the better the capacity of soils to sequestrate atmospheric carbon.
Healthy veld through improved veld management practices thus has the potential to contribute greatly to the reduction of atmospheric carbon and its detrimental effects on people and the environment.
Email Dr Louis du Pisani at [email protected].